The present invention is concerned with a miniature microdevice package and a process of fabricating such a miniature microdevice package. Miniature microdevice packages are made for miniature microdevices such as accelerometers, digital micromirrors, emitters and detectors. Several of these miniature microdevices also require a window transparent to radiation at wavelength of device operation.
Various microdevices achieve their maximum performance when operated in vacuum or in controlled gas atmosphere with a predetermined pressure range. Examples of such devices are miniature accelerometers, digital micromirror devices, miniature radiation emitters and thermal detectors such as bolometers, pyro-electric devices and thermopiles. These microdevices are packaged in hermetic vessels called packages. In addition to providing the controlled operational atmosphere, the packages provide a mechanical protection to often very fragile microdevices made by micromachining of silicon, other semiconductor materials as well as glasses. In the case of the microdevices emitting, modulating or detecting electromagnetic radiation of a determined wavelength, the corresponding package has to be equipped with a radiation transparent window. Practically for all devices, the package has also to be equipped with the conducting feedthroughs providing an electrical contact to the microdevice enclosed in the package.
Known in the art is U.S. Pat. No. 5,420,419 by WOOD, which discloses a method of hermetic packaging by making use of a macro vessel with lateral dimensions often exceeding few centimeters. In this method, it is difficult to miniaturize the whole packaged device because the whole device dimensions are determined by the vacuum vessel, no matter how small the microdevice enclosed in the vessel can be made. The whole packaging process is quite intricate and requires expensive parts such as metal vessel equipped with a plurality of leads, a pump-out tube and a relatively large window. The packaging can only be performed one die at a time which reduces the manufacturing throughput and increases the cost.
Also known in the art is U.S. Pat. No. 5,914,488 by SONE. This patent discloses that the window is directly attached to the semiconductor die with a small hermetic cavity between this semiconductor substrate and the window. This concept of micropackaging has been further developed, as described in U.S. Pat. No. 5,895,233 by HIGASHI et al. and U.S. Pat. No. 6,036,872 by WOOD wherein the package is made entirely of two thin silicon wafers which is quite fragile thus providing a limited protection to sometimes extremely fragile microdevice.
Other U.S. patents such as: U.S. Pat. Nos. 4,701,424 (MIKKOR); 5,397,897 (KOMATSU et al.); 5,459,351 (BENDER); 5,521,123 (KOMATSU et al.); 5,528,452 (KO); 5,585,311 (KO); 5,729,019 (KRAFTTHEFER et al.); 6,062,461 (SPARKS et al.) do not provide packages for microdevice that are both robust and cost effective.
An object of the present invention is to provide a miniature microdevice package that is less fragile than prior art microdevice packages, and is also cost-effective.
According to the present invention, there is provided a miniature microdevice package comprising:
a miniature frame substrate made of a material selected from the group including: ceramic, metal and a combination of ceramic and metal, the miniature frame substrate having a spacer delimiting a hollow; and
a microdevice die having a microdevice substrate, a microdevice integrated on the microdevice substrate, bonding pads integrated on the microdevice substrate, and electrical conductors integrated in the microdevice substrate for electrically connecting the bonding pads with the microdevice, the microdevice die being mounted on the spacer to form a chamber, the microdevice being located within the chamber, the bonding pads being located outside of the chamber.
According to the invention, there is also provided a miniature microdevice package comprising:
a miniature frame substrate made of a material selected from the group including: ceramic, metal and a combination of ceramic and metal, the miniature frame substrate having a spacer delimiting a hollow;
a microdevice die having a microdevice substrate, a microdevice integrated on the microdevice substrate, bonding pads integrated on the microdevice substrate, and electrical conductors integrated in the microdevice substrate for electrically connecting the bonding pads with the microdevice, the microdevice die being mounted on the spacer to form a chamber, the microdevice being located within the chamber, the bonding pads being located outside of the chamber, the miniature frame substrate being shaped to form a channel for pumping air out of the chamber, the miniature frame substrate being provided with a window for allowing radiation inside the chamber, the window being mounted in a recess provided in the miniature frame substrate; and
a plug for sealing the channel.
According to the invention, there is also provided a miniature microdevice package comprising:
a miniature frame substrate made of a material selected from the group including: ceramic, metal and a combination of ceramic and metal, the miniature frame substrate having a spacer delimiting a hollow; and
a microdevice die having a microdevice substrate, a microdevice integrated on the microdevice substrate, bonding pads integrated on the microdevice substrate, and electrical conductors integrated in the microdevice substrate for electrically connecting the bonding pads with the microdevice, the microdevice die being mounted on the spacer to form a chamber, the microdevice being located within the chamber, the bonding pads being located outside of the chamber, the miniature frame substrate having a recess in which the spacer is located, for receiving the microdevice die, the microdevice substrate being soldered on the spacer;
electrical contacts being integrated in the miniature frame substrate for providing electric accesses; and
solderable layers for electrically connecting the bonding pads of the microdevice die to the electrical contacts.
According to another aspect of the present invention, there is provided a process for making a miniature microdevice package, comprising steps of:
(a) shaping a spacer in a miniature frame substrate made of a material selected from the group including: ceramic, metal and a combination of ceramic and metal;
(b) providing a microdevice die having a microdevice substrate, a microdevice integrated on the microdevice substrate, bonding pads integrated on the microdevice substrate, and electrical conductors integrated in the microdevice substrate for electrically connecting the bonding pads with the microdevice; and
(c) mounting the microdevice die on the spacer to form a chamber, the microdevice being located within the chamber, the bonding pads being located outside of the chamber.
According to yet another aspect of the present invention, there is provided a process for making miniature microdevice packages, comprising steps of:
(a) shaping spacers in a miniature frame substrate made of a material selected from the group including: ceramic, metal and a combination of ceramic and metal;
(b) providing microdevice dies each having a microdevice substrate, a microdevice integrated on the microdevice substrate, bonding pads integrated on the microdevice substrate, and electrical conductors integrated in the microdevice substrate for electrically connecting the bonding pads with the microdevice;
(c) mounting the microdevice dies respectively on the spacers to form chambers, the microdevices being respectively located within the chambers, the bonding pads being located outside of the chambers; and
(d) sawing the miniature frame substrate to obtain the miniature microdevice packages.
According to still another aspect of the present invention, there is provided a process for making miniature microdevice packages, comprising steps of:
(a) shaping spacers in a miniature frame substrate made of a material selected from the group including: ceramic, metal and a combination of ceramic and metal;
(b) providing microdevice dies having a common microdevice substrate, each of the microdevice dies having a microdevice integrated on the common microdevice substrate, bonding pads integrated on the common microdevice substrate, and electrical conductors integrated in the common microdevice substrate for electrically connecting the bonding pads with the microdevice;
(c) mounting the common microdevice substrate with the microdevice dies respectively on the spacers to form chambers, the microdevices being respectively located within the chambers, the bonding pads being located outside of the chambers; and
(d) sawing the miniature frame and microdevice substrates to obtain the miniature microdevice packages.